1. Field of the Invention
This invention relates to a device which locks the ejection tip of a hypodermic syringe and a hypodermic needle carried thereon within a protective shield, so that the needle can be safely discarded, and unauthorized re-use thereof is prevented.
2. Brief Description of the Prior Art
In the medical knowledge and understanding of various communicable diseases of the present day, it is well understood that the blood may carry viruses or microbial entities which are active instrumentalities in the transmission of disease from one individual to another. Blood which is thus "contaminated" must therefore be limited in its susceptibility to human contact outside the body of the carrier so that the exposure of medical personnel or others who may be in close association with the carrier of the communicable disease is minimized. In situations, for example, where the carrier is a patient and the medical procedure being performed requires exposure to the patient's blood, it may be important that no contact of the blood of the patient with the physician or other medical personnel occurs.
One frequently performed medical procedure involves piercing the skin of the patient to administer hypodermic injections of medicaments or nutrients, or to extract body fluids for analysis and testing. This procedure poses a risk of transmission of communicable disease through the contact of the blood or body fluids of the patient with medical personnel, or the inadvertent introduction of a miniscule amount of such blood or body fluids into the blood stream of such personnel (through a scratch, exposed abrasion or the like).
An especially intense concern has recently arisen in the case of the disease called "acquired immune deficiency syndrome" (AIDS) because it is well known that this disease is transmitted with the blood of an infected person, and because of the fact that the disease, without presently known exception, is fatal when contracted. Because of the rapid, near epidemic spread of the AIDS disease and the knowledge that one source of contraction of the disease is contaminated blood, it has become a great concern that hypodermic needles and syringes used for drawing blood, or for injecting medicaments or the like into the body of a patient for medical or dental purposes, be used only once, and then disposed safely and with finality, so that personnel may not inadvertently use the same needle for a second injection, or for withdrawal of body fluids, or may not become inadvertently and accidentally scratched by the exposed point of such a once used hypodermic needle, or contaminated by body fluids exposed upon the barrel or tip of the syringe.
It is also understood, from the concerns of medicine with the transmission of various social diseases, and with the arresting and reversal of the wide spread practice of drug abuse, that the repeated use of inadequately cleaned hypodermic needles by persons who abuse drugs of the type which are taken intravenously and by subcutaneous injection poses a real threat of the transmission of certain social diseases, including AIDS, from one person to another. Persons who are addicted to the use of drugs taken intravenously generally utilize syringes and hypodermic paraphernalia for accomplishing various injections of such drugs into the blood stream. Because of the frequent disregard of such persons for the cleanliness or the source of hypodermic needles and syringes used for practicing their habit, it is highly desirable that hospitals, clinics and other places where great numbers of hypodermic syringes and needles are to be used and then discarded take great care in the disposal of these devices. These devices should be discarded in a way such that they cannot be picked up and re-used by such persons who are careless in such use, and who may lack adequate funds or motivation to procure new and medically sterile syringes for the purpose of practicing such drug injection habits.
Recently, strict rules and procedures have been placed in effect which undertake to assure that hypodermic needles and syringes and hypodermic injection devices used in hospitals and clinics are disposed of in a way which prevents their re-use, and assures that they are safe from inadvertent contact.
Various devices and apparatus have been proposed for securing and for shielding the tip and body of a syringe and hypodermic needle from view and from contact prior to actual use. For example, in Gabriel U.S. Pat. No. 2,845,065, a flexible and resilient element in the form of a sleeve or tubular element is placed over the hypodermic needle carried at the lower end of the syringe barrel. This sleeve is forced, by contact with the body, at the time of a hypodermic or subcutaneous injection, to move toward the syringe barrel in a direction which allows the needle to become exposed, and to penetrate the body. Prior to this time, and even at this time, the needle has not been visually perceptible, and may remain invisible because of the extension of the sleeve to the point of injection, at which point the sleeve bears against the skin and surrounds the point where the needle pierces the skin.
This device is, of course, constructed in this way primarily to prevent those who have a phobia about the use of needles for administering hypodermic injections from being as alarmed or frightened as would otherwise be the case if the needle were in full view. Such devices, after functioning to hide the needle until the time of injection, can be returned to a shielding position where the needle is again surrounded and obscured from view following the injection. The very nature of such flexible and resilient sleeves which permit them to be forced back with little pressure from the body when a shot is to be given, and the sleeve contacts the body, also prevents such a sleeve from affording any very significant protection for the needle because such sleeve can be easily forced back to a position where the needle can be inadvertently contacted, and can even be re-used if such is attempted.
Another device which is intended to hide from view the needle associated with the hypodermic syringe until the instant of injection is depicted and described in U.S. Pat. No. 2,571,653 to Bastien. In the Bastien patent, a syringe is provided which is a conventional hypodermic syringe, but which is fitted with a concealing tubular sheath fitted over one end of the barrel. The sheath is slidable along the barrel between two positions to which it is indexed by means of a small latch which projects through the side of the sheath and consecutively engages a pair of grooves formed in the outer surface of the syringe barrel at axially spaced locations. In the use of the Bastien syringe, the person who is to administer an injection with the syringe initially fills the syringe with a medicament to be injected, and then places the sheath over the lower end of the barrel so that the latch is engaged with the lower of the annular grooves formed around the barrel. The sheath at this time obscures or prevents view of a needle carried on the lower end of the barrel.
When the injection is administered, the person administering the injection pulls a handle of the sheath and pushes a handle of the barrel, so that the two move relatively toward each other, thus causing the sheath to move upwardly along the barrel until the latch enters the second groove. At this time the needle is exposed and the injection can be given. This procedure is reversible so that the sheath can be re-set to an obscuring, or view-blocking position, if desired, thus permitting the syringe to be re-used any number of times desired. The latch is made so it can be easily popped in and out of either of the annular grooves in the barrel simply by the operator's finger pressure. The Bastien device therefore does not afford any significant protection against re-utilization of the syringe and the needle which it carries, and against consequent contamination of any unauthorized users or persons who may inadvertently become scratched by the exposed needle.
Another deficiency of the Bastien device as a protective assembly which cannot be easily moved to a position in which access can be had to the needle is that the mechanism which effects the temporary latching is exposed on the outer side of the sheath, and can therefore be easily destroyed or rendered inoperative by anyone. Little or no significant force or strength is required to do so to effect the unlatching of the barrel from the sheath.
A hypodermic syringe assembly which temporarily protects or covers the needle of the syringe is shown in Bower U.S. Pat. No. 2,674,246. Here, however, the principal objective of the Bower hypodermic syringe construction is simply to conceal the needle from a patient until the instant of injection. The concealing tubular member or guide which surrounds the needle is spring biased outwardly to a position where it will hide the needle from view. Finger pressure on the barrel of the syringe is sufficient, however, to overcome the bias of the spring, and to cause the needle to be extended out the end of the protective sleeve or tube and through the skin of the patient. There is therefore no safe position which precluded unauthorized use of the needle, and indeed, merely dropping the device would apparently cause its spring to be compressed sufficiently to permit the needle to scratch the skin if it should inadvertently fall against the leg or foot of a person.
Another manually operable syringe device which obscures or hides the needle from view prior to use of the needle is that which is shown in Sagstetter U.S. Pat. No. 4,664,653. The Sagstetter injection apparatus is, however, intended to be reusable, and the entire syringe unit can be removed from the protective housing following the administration of the initial injection. After such removal, the needle is covered only by a flexible, easily penetrable sleeve.